671 research outputs found
Special Section Guest Editorial: Detectors for Astronomy and Cosmology
This guest editorial summarizes the Special Section on Detectors for Astronomy and Cosmology
Regional mean sea surface and mean dynamic topography models around Malaysian seas developed from 27 years of along-track multi-mission satellite altimetry data
Contemporary Universiti Teknologi Malaysia 2020 Mean Sea Surface (UTM20 MSS) and Mean Dynamic Topography (UTM20 MDT) models around Malaysian seas are introduced in this study. These regional models are computed via scrutinizing along-track sea surface height (SSH) points and specific interpolation methods. A 1.5-min resolution of UTM20 MSS is established by integrating 27 years of along-track multi-mission satellite altimetry covering 1993–2019 and considering the 19-year moving average technique. The Exact Repeat Mission (ERM) collinear analysis, reduction of sea level variability of geodetic mission (GM) data, crossover adjustment, and data gridding are presented as part of the MSS computation. The UTM20 MDT is derived using a pointwise approach from the differences between UTM20 MSS and the local gravimetric geoid. UTM20 MSS and MDT reliability are validated with the latest Technical University of Denmark (DTU) and Collecte Localisation Services (CLS) models along with coastal tide gauges. The findings presented that the UTM20, CLS15, and DTU18 MSS models exhibit good agreement. Besides, UTM20 MDT is also in good agreement with CLS18 and DTU15 MDT models with an accuracy of 5.1 and 5.5 cm, respectively. The results also indicate that UTM20 MDT statistically achieves better accuracy than global models compared to tide gauges. Meanwhile, the UTM20 MSS accuracy is within 7.5 cm. These outcomes prove that UTM20 MSS and MDT models yield significant improvement compared to the previous regional models developed by UTM, denoted as MSS1 and MSS2 in this study
The FLASHES Survey I: Integral Field Spectroscopy of the CGM around 48 QSOs
We present the pilot study component of the Fluorescent Lyman-Alpha
Structures in High-z Environments (FLASHES) Survey; the largest integral-field
spectroscopy survey to date of the circumgalactic medium at . We
observed 48 quasar fields between 2015 and 2018 with the Palomar Cosmic Web
Imager (Matuszewski et al. 2010). Extended HI Lyman- emission
is discovered around 42/48 of the observed quasars, ranging in projected,
flux-weighted radius from 21-71 proper kiloparsecs (pkpc), with 26 nebulae
exceeding in effective diameter. The circularly averaged
surface brightness radial profile peaks at a maximum of
( adjusted for
cosmological dimming) and luminosities range from
to
. The emission appears to have a highly
eccentric morphology and a maximum covering factor of ( for giant
nebulae). On average, the nebular spectra are red-shifted with respect to both
the systemic redshift and Ly peak of the quasar spectrum. The
integrated spectra of the nebulae mostly have single or double-peaked line
shapes with global dispersions ranging from to
, though the individual (Gaussian) components of lines
with complex shapes mostly appear to have dispersions
, and the flux-weighted velocity centroids of the lines
vary by thousands of with respect to the systemic QSO
redshifts. Finally, the root-mean-square velocities of the nebulae are found to
be consistent with gravitational motions expected in dark matter halos of mass
. We compare these results to existing
surveys at both higher and lower redshift
Revisiting FUSE O VI Emission in Galaxy Halos
A significant fraction of baryons in galaxies are in the form of diffuse gas
of the circumgalactic medium (CGM). One critical component of the multi-phases
of CGM, the so-called "coronal" warm-hot phase gas ( K)
traced by O VI 1031.93, 1037.62 \r{A} resonance lines, has rarely been detected
in emission from galaxy halos other than Milky Way. Here we report four
additional detections of O VI emission gas in the halos of nearby edge-on
galaxies, NGC 4631 and NGC 891, using archival Far Ultraviolet Spectroscopic
Explorer data and an updated data pipeline. We find the most intense O VI
emission to be from fields forming a vertical line near the center of NGC 4631,
despite the close proximity to the disk of two other fields. The detected O VI
emission surface brightness are about 1.1 to
3.9 ergs s cm arcsec. The
spatial distribution of the five 30" 30" O VI detection fields in NGC
4631 can be interpreted as the existence of filamentary structures of more
intense O VI emission superimposed within a diffuse and faint O VI halo in
star-forming galaxies. Volume-filled O VI emission mapping is greatly needed to
determine the structure and prevalence of warm-hot gas and the role it plays in
the cycling of gas between the galaxy disk and the halo. Finally, we present
the sensitivity of future funded and proposed UV missions (LUVOIR-A, LUVOIR-B,
CETUS, and Aspera) to the detection of diffuse and faint O VI emission in
nearby galaxy halos.Comment: 12 pages, 5 figures, accepted for publication in Ap
Fesselin and caldesmon: natively unfolded proteins in smooth muscle regulation
Dysregulation of smooth muscle contraction is linked to diseases such as atherosclerosis, asthma, hypertension, urinary incontinence, premature birth and others. The goal of this project is to contribute to our understanding of the mechanisms of smooth muscle regulation. Caldesmon and fesselin are actin-binding proteins abundant in smooth muscle that have multiple binding partners and are well positioned to alter smooth muscle contraction. Because fesselin is a heat-stable proline rich protein that has many properties in common with the natively unfolded COOH terminal fragment of caldesmon, we sought to determine whether fesselin is natively unfolded. We compared fesselin to a known globular protein (myosin S1) and the unfolded C-terminal 22 kDa fragment of caldesmon (CaD22) using techniques such as gel filtration, intrinsic tryptophan fluorescence and circular dichroism. We showed that fesselin is a natively unfolded protein. We also investigated the effects of phosphorylation by p21-activated kinase 3, PAK, and calmodulin on CaD22. We found a novel regulatory region between the residues 627-642 in the unfolded caldesmon C-terminus and identified four minor residues slowly phosphorylated by PAK. Phosphorylation of this region alters both the ability of caldesmon to inhibit actomyosin ATPase and the interactions between caldesmon and Ca2+-calmodulin that may contribute to the overall regulation of caldesmon's activity.  Ph.D
Optimizing Production Sharing Contract For Marginal Fields Development
This study proposes an optimized production sharing contract that promote the development of marginal fields by protecting the contractor’s downside while enabling the government to increase its rightful share in case of profitability increment.
A marginal field model is developed based on pseudo field that was assumed in reference to commonly accepted exploration and development data that are typical in Nigeria. The economic analysis of this model involves cash flow modeling, profitability analysis, and sensitivity analysis.
The parameters of the PSC are varied to analyze the effect of each provision, and to identify which combination of variables will ensure a fair division of benefits and risks between the government and the contractor
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